Beyond Platelet Count: Rethinking Platelet-Rich Plasma Efficacy Through Growth Factor Biology and Functional Quality

The efficacy of platelet-rich plasma (PRP) has long been associated with platelet concentration, yet clinical outcomes remain highly variable and frequently inconsistent. This review challenges the assumption that platelet count alone defines PRP efficacy, proposing instead that functional platelet quality and growth-factor bioactivity are equally critical determinants of therapeutic outcomes. Platelets act as carriers of bioactive molecules stored within alpha granules, including growth factors such as platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-β), vascular endothelial growth factor (VEGF), and insulin-like growth factor (IGF), which orchestrate the cellular and molecular events of tissue repair. Variations in donor biology, age, metabolic status, and oxidative stress profoundly influence platelet functionality and growth-factor release. Likewise, centrifugation parameters, temperature control, and activation methods dictate whether these mediators are preserved or prematurely exhausted. Collectively, these findings reveal that platelet number alone cannot predict regenerative potency. The future of PRP standardization requires the integration of platelet quality indices, growth-factor quantification, and patient optimization protocols into clinical practice. By shifting focus from platelet enumeration to bioactivity assessment, regenerative medicine can achieve more consistent, personalized, and scientifically accurate outcomes.